Hazardous materials, whether they are raw materials or waste byproducts, are essential to many industries. These industries must inventory or stockpile a significant amount of these materials in order to satisfy their daily manufacturing needs or disposal schedules. Unfortunately, any significant collection of hazardous materials, whether they are toxic, radioactive, explosive, corrosive or highly reactive in some other way pose a threat to the environment and to people nearby. Active chemicals may be leaked into the surrounding atmosphere and cause injuries to nearby workers or residents. Chemical fires are often hard to extinguish and can cause significant damage. Radioactive leaks and toxic dumping can have severe long-term effects and often attract vast amounts of public attention even when the risk of injury is not great. Society, in general, has become increasingly aware of the risk of injury and, as a result, industries are being required to contain or reduce the risks.
Industries are developing new techniques for storing hazardous, toxic and radioactive materials partly due to regulatory mandate and partly on their own initiative. Instead of simply dumping toxic chemicals or other industrial wastes in a spare corner of the plant site, industries are being required to storehouse these materials until they can be shipped to an approved dumping site. Instead of stockpiling chemical reagents and other dangerous materials in a fenced back lot, industries are being required to contain these materials in sealed steel or cement containers to prevent them from leaking into the air or from igniting spontaneously.
These new techniques create new problems. Hazardous chemicals, be they radioactive or chemically active, are typically stored in steel or plastic drums which are in turn stockpiled in steel or cement containers or buildings. Locked away in their sealed buildings, the individual barrels are difficult to monitor. Leaks, or chemical changes inside the containers can result in hazardous conditions for workers who must enter the building or in explosions which can endanger nearby people and structures.
Hazardous materials also pose these same risks when they are not in storage. Laboratories, manufacturing plants, and even parking and office structures use or are exposed to hazardous materials which can endanger people and structures. While the problems posed by hazardous materials outside of storage containers are not new, society's concern for these risks is increasing.
Presently there exist a variety of sensors which may be adapted to determine whether a hazardous condition exists within a container or other environment. However, no system exists for determining the level of the hazard and automatically taking a corrective measure to alleviate the hazard or alternatively warning of a hazard which cannot be reliably alleviated.
Sensing and recording devices are available in a variety of configurations. U.S. Pat. No. 4,526,028 to Hubner, for example, shows a system capable of measuring, displaying, and recording a variety of atmospheric parameters; for example, temperature, humidity, air pressure and noxious gas concentration. If the concentration of noxious gases becomes too high, an alarm will sound. Typical household smoke detectors similarly measure the presence of smoke and sound an alarm if the concentration exceeds a predefined threshold. In large buildings, smoke levels are detected at a variety of satellite locations to sound a control alarm. These systems, however, do nothing to alleviate the smoke hazard or the presence of noxious gases.
U.S. Pat. No. 3,826,180 to Hayashi shows a ventilation fan system with a smoke detector speed control. This device includes a circuit to activate the fan when a smoke or gas from a cooking range is detected to ventilate a kitchen. U.S. Pat. No. 4,338,526 to Martin and U.S. Pat. No. 4,404,651 to Duhame show gas and smoke detectors which open a garage door when the level exceeds a predefined threshold. The garage door opener is integrated into a home security system. U.S. Pat. No. 4,308,911 to Mandl shows a system which integrates smoke detector, security and air conditioning systems using a computer. The Duhame system simply operates an alarm in response to excess smoke, however.